TUESDAY, April 30 (HealthDay News) -- For the many pregnant women who are concerned about how beauty products, such as hair dyes and skin creams, will affect their developing baby, an expert offers some advice on what is safe.

"Women face a lot of uncertainty as their bodies change during pregnancy, and many worry about how to look their best," Dr. Mary Rosser, of the department of obstetrics and gynecology and women's health at Montefiore Medical Center, said in a Montefiore news release.

"We work hard to separate truth from fiction to put mothers at ease and help them figure out ways to make this special time in their lives consistent with the way they're used to living and looking," Rosser explained.

Women should try to avoid using hair dyes during pregnancy, she advised. Pregnant women who want to color their hair should do so after the first trimester and in a well-ventilated space. Women should tell their hair stylist that they are pregnant and ask them to try to prevent the chemicals from touching their scalp, Rosser noted.

The main concern with hair dyes is breathing the ammonia fumes that could be harmful to the developing baby in the first three months of pregnancy. The fumes in hair straightening products are also an issue, she said.

Highlights are considered safer because the dye is enclosed in foil and won't be absorbed into the skin. Rosser added that vegetable dyes such as henna are likely the safest choice during pregnancy.

Pregnant women can get a standard manicure after the first trimester, when the risk to the developing baby is lower. Check that the instruments have been sterilized and ask the nail technician not to cut the cuticles. This will prevent exposure to germs, according to Rosser, who is also an assistant professor in the department of obstetrics and gynecology and women's health at Albert Einstein College of Medicine of Yeshiva University, in New York City.

Pregnant women should avoid acrylic nails. The chemicals and adhesives can contain cyanoacrylate, which can be harmful. This substance can be inhaled in the dust when nails are filed, so wear a mask and make sure there is proper ventilation in the nail salon, Rosser suggested.

Pregnant women with acne should wear oil-free cosmetics and wash their face twice a day with a gentle cleanser and lukewarm water. If acne persists, ask your doctor for a prescription for erythromycin. Do not use Retin A or tetracycline, which can cause birth defects, Rosser warned.

Wearing sunscreen can prevent dark circles around the eyes and darkening pigment of the skin. Rubbing vitamin E on the areas most likely to be affected by stretch marks may be helpful, she noted.

"The most important thing to remember is that this is a happy time in your life and you are beautiful just by nature of being a pregnant woman," Rosser said. "As long as you make smart choices, get plenty of rest, drink lots of water and eat a healthy, balanced diet, you can enjoy your pregnancy, look and feel good, and have a healthy baby!"